- Why Do I Need to Cut Concrete?
- Is a Circular Saw the Best Tool for Cutting Concrete?
- The Hazards of Concrete Cutting
- Safety Precautions When Cutting Concrete
- What Blade For Concrete Cutting?
- How to Cut Concrete With a Circular Saw
- What You Will Need to Follow This Tutorial
- How To Perform Concrete Cutting With a Circular Saw — Step By Step Instructions
- Dos and Don’ts of Concrete Cutting
- When to Cut Concrete
- Concrete Cutting With a Circular Saw FAQs
The idea of cutting cement-based masonry can initially be intimidating. However, with the correct tools, safety precautions, and techniques — it’s actually more straightforward than you think.
Being able to competently cut this material opens up a whole new world of DIY projects — hence why it’s important to me to pass on my knowledge in this technical area.
In this article, I’m going to provide you with a veritable concrete cutting 101 — including addressing brickwork and cement — revealing pro tips and hacks to ensure rewarding results, while keeping hazards to the minimum.
Why Do I Need to Cut Concrete?
Considering concrete is supposed to be a long-lasting, semi-permanent medium — it seems incongruous that you would consider cutting it.
However, there is a multitude of reasons that you may need to remove sections, create channels, or generally reshape masonry.
Although not an exhaustive list, here are the most popular grounds for addressing brickworks and concrete with a circular saw:
- Resizing patio slabs or brick paving.
- Demolition projects.
- Creating expansion joints in solid cement flooring.
- Channeling walls for electrical wiring or piping.
- Repairing sub-concrete sewer waste lines.
- Fixing and replacing sections of masonry.
- Garden and patio landscaping.
Is a Circular Saw the Best Tool for Cutting Concrete?
What IS the best tool for concrete cutting is a saw with a rotary blade — as featured in circular models.
Bandsaws are too weedy, concrete would rip the chain off a chainsaw, and miter saws are too small and impractical — never mind the fact they’re designed for addressing timber.
The beauties of masonry shaping by a saw with a rotary action — i.e. where a toothed disc spins around a central arbor — are:
- The high rotation rate delivers the grunt for tackling dense material.
- Minimal surface area contact reduces friction and loss of power.
- Consistent spinning motion.
- Accurate control.
However, when it comes to cutting concrete — all circular saws aren’t created equal. It’s akin to naming all four-legged animals as camels.
The broad spectrum of circular saws includes table saws, miter saws, rip saws, and handheld woodworking saws. Attempt to use any of these examples to shear through concrete — and you’ll end up with a broken machine, wrecked concrete, and probably find yourself in the Emergency Room.
What you need for tackling hardcore masonry work is a circular saw that has the grunt to drive through dense material, a handheld design to allow for vertical or horizontal work, and the compatibility with blades suited to plowing through brickwork.
Yet, even when you have a tool that meets all the above requirements — it can still be less than ideal. Due to the hazards involved in concrete demolition and cutting — ideally, you need a bespoke concrete cutting saw.
The Hazards of Concrete Cutting
Look at your walls, patio, or driveway — or whatever is close by that’s made from this material. It just sits there, day after day, pretty much unchanging — causing you no harm, concerns, or troubles whatsoever.
Yet, you know how your wife/girlfriend’s demeanor suddenly changes when you politely enquire whether she’s gained a little weight? That’s the same as when you cut concrete.
Slicing through this material with a circular saw unleashes an entire Pandora’s Box of unpleasantness, including:
- Bullet-like shards of aggregate shooting towards your face.
- Hazardous carbon monoxide fumes (with gas-powered tools).
- Airborne silica dust — causing asthma, cancer, and silicosis.
- Tool overheating danger.
- Limb-endangering blade kickback.
Thankfully, by using a circular saw designed for concrete cutting — these risks can be minimized.
Safety Precautions When Cutting Concrete
I know I’m stating the darn obvious, but it’s crucial you wear protective equipment. Not only are you dealing with a volatile material in concrete, but you’re also wielding a dangerous weapon.
At the very least, ensure that you don:
- Protective goggles.
- Work-site grade gloves.
- Respirator mask.
- Ear defenders.
- Steel-toe-capped boots.
- Thick overalls.
As mentioned earlier, using the correct tool is essential for masonry channeling, shearing, or slicing. Always check with the manufacturer that their tool is suitable for addressing concrete.
Your cutting saw should:
- Have a blade designed for concrete.
- Feature a water line — to cool the blade and minimize airborne dust.
- Incorporate a dust/fume vacuum extractor.
- Possess substantial blade and handle guards.
- Be well maintained.
In addition to the above precautions, sensible concrete cutting practice includes:
- Working in a well-ventilated area.
- Ensuring water slurry is cleaned up frequently to prevent slippage.
- Use long, slow, deliberate passes.
- Checking the blade is undamaged.
- Keeping children, pets, and your wife away from the working area.
- Avoiding hacking at the masonry.
- Ensuring no risk of structural collapse.
- Not wearing loose clothing.
- Keeping long hair and beards away from the blade.
- Not cutting below knee level or above shoulder height.
- Checking for hidden pipes and electrical wiring before commencing work.
- Taking frequent breaks — allowing you to maintain focus and preventing vibration injuries.
What Blade For Concrete Cutting?
Diamonds might be a girl’s best friend — but they’re also the best buddies of concrete cutting DIYers and trade pros. In short, there’s no other edge with the durability and sharpness to deal with masonry materials.
There are four key components of a quality, concrete-suitable, diamond blade:
1. Metal core — a reinforced steel disc with a rim that houses the diamonds.
2. Diamonds (synthetic) — providing a honed edge for cutting.
3. Matrix — the metal bond that adheres the diamonds to the steel disc.
4. Weld — connecting the cutting segments to the metal interior core.
The strength and sharpness of the diamonds slice through the concrete while the disc rotates at a rapid velocity. Naturally, over time, these synthetic crystals become worn and fall away — exposing fresh, shiny, brand-new stones incorporated into the matrix.
For masonry shearing applications, there are two forms of diamond cutting blade — dry and wet.
Diamond Dry-Cutting Blade
That said, they can still eventually overheat and will create dust. Hence, they’re typically used for short, small concrete projects on low-grunt circular saws.
Diamond Wet-Cutting Blade
Water cooled, these cutting edges are ideal for long projects that involve deep cuts with mammoth horsepower tools — that is, where temperatures can be high. Furthermore, the water acts to trap the dust — reducing the volume of airborne contaminants that can be a respiratory risk.
While you can utilize a separate hose pipe to distribute water on the blade and concrete — it’s seriously inadvisable due to slippage and electrocution risks. Instead, choose a concrete cutting saw with an incorporated water line.
How to Cut Concrete With a Circular Saw
What You Will Need to Follow This Tutorial
Before we get started, check you have the following materials and tools (those that are applicable to your current project) readily to hand. It will help to prevent unnecessary downtime once you start the job — and eliminate frustrations.
- Suitable wet concrete cutting saw.
- Wet diamond blade.
- Water supply/hose/connectors.
- Vacuum for dust extraction (where applicable to your saw).
- 2 x 4 timber plank.
- Builders chalk.
- Personal safety equipment.
- Masking tape.
- Wire brush.
- Hammer and chisel.
- High abrasion sandpaper.
How To Perform Concrete Cutting With a Circular Saw — Step By Step Instructions
Dos and Don’ts of Concrete Cutting
- Do use a circular saw specifically designed for cutting concrete.
- Do wear safety equipment.
- Don’t force the blade.
- Do use water on the blade.
- Don’t slice through load-bearing concrete lintels or walls.
- Don’t use the saw for more than 45 seconds continuously — remove from the concrete and run free to allow for cooling.
- Don’t try to cut through concrete with internal steel reinforcement.
- Don’t bend or twist the saw blade edge when cutting.
When to Cut Concrete
Although many of your cutting projects will involve addressing established masonry — for example, when performing repairs on cracked flooring — other jobs may involve tackling freshly laid concrete.
And, while it’s understandable that you want to complete your masonry work as soon as possible — be patient!
It’s crucial that you allow sufficient time for your newly-created cement mix to dry before slicing with your saw. Engaging with it prematurely can weaken the material, increase the likelihood of splits, and cause raveling — an issue where the blade draws aggregate out of the fresh concrete, meaning a sharp, messy, and dangerous edge.
Factors that affect the drying time include:
- Ambient humidity.
- Access to sunlight.
- The ratio of aggregate, sand, and cement.
- Wind level.
- The porosity of the material beneath the concrete.
Hence, there is no hard or fast set rule to the length of concrete drying time — it can be anywhere from four to 72 hours. To check whether your new masonry is ready to address — first perform some small initial test cuts on an inconspicuous area to check for raveling or cracking.
If I was to leave you with one single piece of advice, it would be this:
Always use a saw designed for concrete cutting — that is, a machine that allows for vacuum dust extraction and utilizes water on the blade.
If you believe any of your buddies could benefit from reading this How-To, please feel free to share!
Concrete Cutting With a Circular Saw FAQs
Q: What Type of Blade Do I Need To Cut the Sidewalk?
To address sidewalks and kerbstones, you need a diamond-edged blade to slice through this dense material. Furthermore, as these prefabricated concrete blocks are often thick — use the largest diameter blade compatible with your particular saw.
Q: I’d Like To Cut 4-Inches Thick Concrete. Will I Have To Cut the Whole 4 Inches of It?
In many circumstances, you can cut halfway into the masonry — to create a cement ‘score’ — and then address it with a sledgehammer to separate the piece.
However, be careful.
Aggregate-heavy mixes can split unevenly — wrecking your handiwork. In these circumstances, it’s best to cut completely through the cement.
Q: Can You Cut Concrete Without Water?
You can — but you need to take additional precautions and alter your cutting technique slightly.
Water helps to control hazardous airborne dust while acting as a cooling agent on the blade. Hence without H2O, contaminants are elevated, as is the temperature of your cutting edge.
Therefore always use a blade designed for dry use — as it has been constructed to dissipate heat. Furthermore, wear high-grade respiratory equipment to protect your health, and don’t run the blade continuously for more than 30 seconds.
Q: How Loud Is a Concrete Cutting Saw?
A typical concrete saw will emit around 100 dBa — sufficient to cause damage to hearing if operated for more than 30 minutes. It’s, therefore, crucial to don ear defenders when using these machines.
Q: Do Diamond Blades Have Real Diamonds?
Yes. The high density of diamonds permits them to slice through concrete.
However, these are not the same quality of precious stones that you obtain from a jeweler. Instead, they are typically cloudy industrial-grade diamonds or synthetic varieties.